Treatment of slurries in rotary kilns



March 26, 1929.

TREATMENT OF SLURRIES IN ROTARY KILNS T. RIGBY Filed Nov. E, 1926 2Sheets-Sheet 1 Invenbr' i March 26, 1929. T. RIGBY TREATMENT oF sLuRRIEs1N RQTARY KILNs Filed Nov. 5, 19.26 2 Sheets-Sheetl 2 E177/ ll /l/IPatented Mar. 26, 1929.

l THOMAS, RIGBY, oF

LONDON, ENGLAND.

TREATMENT ory SLURRIES IVN ROTARY KIILN'S.: ,l

Application fue@ November 5, 192e, serial Nq. v146,515, arid inermiBrii'amlNovember V15, 1925'.

This invention is concerned with the treatment of materials, such ascement-makin g materials, by wet methods in rotary kilns by atomizing orsimilarly dispersing a slurry of the material or materials in a finelydivided The invention is particularly (though noty exclusively)vconcerned with improvements in or modifications of the inventions'v setforth in my'pendi'ng applications Serial Nos. 44,865 and 121,184. V YFigure 1 is ment according to the invention in r`which the kiln isdivided into two separated parts; o' Figure Q, is a view on thelineofFigure 1 looking in the direction ofthearrows;

Figure 3 is a planview of another arran`gea ment ofv thetype shownFigure 1; and

Figure 4L is side elevation of still `an other arrangement of this type.

ln the arrangements illustrated it. willA be Y seen that measures havebeen adopted tov structurally separate that hotter port-ion of a kilnwhich operates upon the ymaterial which hasralready' collected upon. thekilnv wall from a coolerportion (which may be regarded as a dryer, andmay be specially constructed in view of this limitation of itsfunctions) in which. is effected dispersal of thev material Ainto thegases` as spray and its collection on the wall 'of Lsaid cooler portionto continue its travel falong the' latter" to the kiln proper. l y d Theseparationof the kiln into two parts in the case of a rotary cementvkilnmay be such that the customary kiln head is retained and used'in thenormal operation of the plant merely as a depositing chamber for..rpurposes such as hereinafter indicated and aia'ataryV cyf l'indricalshell of much the same cross-sec-V tional dimensions as the kiln can bekprovided o' to rotate, for example, on an axis parallelto, the kilnaxis but at a somewhat lng-her level andwith its lower end opening intothe reary wall of the kiln head aforesaid. and its upper end yopeninginto the front iliary kiln head or the like. The partly dried materialtumbling ont of the lower end of the shell willpreferably be allowed tofallaeross 'the space in the1first-mentionedy kiln head into the mouthof the kiln `proper over a" vchute. l, .v

a side elevationof one arrangewall of an aux-y d Such. an arrangement isshown in Figures 1 and 2wher`ein the rotary cylindrical shell is shownat 70, the Vchute leadingv to the kiln 7 is shown at 6() and ana'uxiliarykiln head Vis shown at 105, this kilnhead and the custom# arykiln head 5 each-being providedv forexample' with va liquid reservoirvat its base toY l' provide therein a vehicle for the ready collectionand withdrawalvfrom the kilnheadfof" deposited f matter. The liquidr inthe kiln head 105fro'm which the'kiln gases may leave the system maybeslurry 'afterwardsfed to yatomiz'mg means, indicated inthis case asdiiecting from points 1() two spraysinto the v cylindrical shell todifferent" regions along itin afmanner described lin my application 'fSerial No. 121,184.1 Y

Such a shell as'70` may, however, discharge,

if preferred, intofone vof the side walls ofl a kiln head 5 andthetransferring chute 60 over which thematerial tumbles into the kiln headfrom the shell to the kilnthen be suitably'niodified. .l i

This is indicated in Figure 3,' the sprays in that instance being shownasoperating in a manner described in my application last men# tioned todeliver sprayto the same general region in the'cylindrical shell 70.`

' Indeed a shell such as 70 neednot open directly into the customarykiln head if that l retained but may as indicated in Figure 4L `have itsend connected.- (fortheflowof the gasinto it and the traveloffthedeposited inavterial from it) to'said kiln head-by a fixed gas L y,

'conduitQ of appropriate dimensions and ar`y ranged so as, orprovided'with means such" as thechute 60, to ensure t-he proper travel by gravityof partly dried material (possibly of doughy Vor clayey consistencyandapt to CO4,

here and pack'into-lumps andl balls) from theshell 7() to the kiln head5. f

With such latter arrangement, the delivery 'i Y lend of the shell 70r(which Vshell ispreferably `but little inclineddownwards .towards lthef delivery end) can be at any desired height relatively to the kilnorthe axis of the cylinndrical shell 70fcan lie in a different verticalplane from that containing the kiln axis.

An important advantage of such a separation vof thedrying alone lor ofthe'drying and part of.` the after treatment or of part ofthe dryingfrom Vthe remainder of the' kilning operationenV operations (such asfurther ,dry-` ing or calcining or clinkering) asis effected y inconstructions; of indicated is the upon Wet slurry in theupperpartei-.thekiln.v

leave behind them necessarily in the slurry certain amounts ofimpurities (suoli as sulphates) which the colnbustionot the uel hasintroduced into them and of a nature and eX- tent capable in somecircumstances of modiyingundesirably the character of the product.

In novel constructions such as indicated the customary kilnhead mayberetained in such a form as to operatein a measure as a settling chamberfor these impurities so that-by the time the gases enter such a shell asto meet Wet slurry therein they have to some extent if not largely beenfreed of such impurities. ln such a ,case partly .dried materialtumbling from-the shell 70 over achute 60 orthe like in the kilnhead 5is preferably shielded from the settling upon it ci `such impurities asby a shield 64; (see Figuresl and 2) ,wvhile it traverses-the stilleratmosphere inthe kiln head and liquid, lor instance Water, passedthrough the bottom tol the ykiln headinay be used to catch the depositedimpurities and act as a vehicle. for their convenientJWithdra-Wal fromsuch head. i

Again'constructions such as indicated lend themselves, b y the additionto an existing kiln and kilnhead of a shell and its own head orthe like,to the modification of eX-isting plant with a minimum of interruptionoi' manufacture so as. to increase to the maXimum possible the output oia givenexistmg plant or to convert a dry kiln plant into ,one Working atvery high eiiiciency on the Wet process. Such change' moreover, can bemade at a lonT plant cost 'since the shell (or at least some of it) andits head need not necessarily7 be adapted to resist relatively hightemperaturesv if provision be made tor by-passing the gases from the.customary kiln head (and may be pvouringrslurry directly into the kilnproper) on failure for any reason of cooling action in theI shell andthese or considerable parts of them may-in such a case be to a largeextent little morethan sheet metal casings merely lagged more or lessagainst heat loss by radiation. Other advantages that accrue lrom such'separation ofthe kiln parts as ret'erred to.are the possibility ofdetermining independently for that' part of the kiln in Whichatomizingis effected (the shell 70 or the like) its inclination,diameter` and speed of rotation so as to best suit these to theellicient carrying outof the part ot thetreatment to which that partofthe kiln is devoted.v

In` any case the slurry lifting shelves or radial plates with which theupper end ol a kiln is usually provided can` in most cases Withadvantagebe dispensed. with in the' shell and the inside of 'the shell left bare.

ln any event an important factor to yobserve is the disposition et'theaxisor axes of such impingement occurs been dried to a sub-v smntial.decree and lost itsrtendency to form. coherent Vmasseson saidavall.

l claimz-- LA, slurry treating plant comprising inA combination a rotarykiln,`a rotary cylindri- A cal shell disposed adjacentthe exit end olthe kiln and through which the kiln' gases flow, means lor spraying slurry-into the cylindrical shell AWliereby a cross-sectionthereof iscompletely filled with a slurry spray which lcross-section slurry fromsaid` spray is gently deposited upon 4the-kiln Wall and has been sodried by the kiln gases that it has llost its vtendency to Ytornicoherent masses onl the shell" wall, and means whereby the materialtreated is passed from said shell to the kiln.

2. A slurry treating plant according to claim l, wherein the axis ol therotary kiln is out pl alignment with that ofthe cylindrical shel 3. A.slur-ry treating plant according Ato claim. l, and a chute overWliiclrtlie material being treated kiln.

fl. A slurry treating plant according to claim l, and a shield. abovesaid chuteto prevent any material 'deposited by the kiln Vgases passesVfrom the shell tothe y as they llow from the kiln to said shell Vtromsettling upon and modiiyin undesirably the material passing alongV thevsaid chute.

5. A slurry .treating plant acxording to claim l, in which the rotarykiln and the cylindrical shell each open into a chamber having at itsbase a liquid reservoir i'for the ready collection and Withdrawal fromthe chamber of deposited matter.`

6. A slurry treating plant according to.

claim l, in which the kiln opens into a kiln head havin at its base aliquid reservoir 'for the collection ol matter deposited from the kilngases and. the cylindrical. shell opens at one en d intov the kilnheadaforesaid and at its other end into a second' kiln head Whichisprovidedat its base with a slurryA reservoir which slurry is afterwardsfed to the spraying means aforesaid, and the cylindrical shell and thekiln .are connected by a chute over Which the partly dried materialpasses from the said shell. into the kiln. p

7. A` slurry treating plant according to -1,7oe,749 i, I o' Y 3 claim l,in which thekiln opens into a kiln reservoir, and a chute over which thepartly head having at its base a liquid reservoir for dried materialtravels from the said conduit the collection of matter deposited fromthe to the kiln. f 10 kiln gases and the cylindrical shell'opens at Intestimony whereof I .aiix my signa- 5 one end into a conduit leading tothe kiln ture. v

head aforesaid and at its other end into a second kiln head which has atits base a slurry y y THOMAS RIGBY.l l i

